Asymmetrical conductor



SYMMETRICAL CONDUCTOR Filed Jan. 29, 1957 COPPER, CONTAINING GADM/UMFIG. 2

INVENTOR G. O. SM/TH 8V mull GA, 7M

A TTORNE Y Patented Sept. 21, 1931 PATENT oFFicE ASYMMETRICAL CONDUCTORGeorge 0. Smith, Bloomfield, N. J.', assignor to Bell TelephoneLaboratories, Incorporated, New York, Y., a corporation of New YorkApplication January 29, 1937, Serial No. 122,989

6 Claims.

-T'his invention relates to devices that offer a greater resistance tocurrent flow in one direction therethrough than in the oppositedirection, and, more particularly, to such devices of the copper-cuprousoxidetype.

An object of this invention is to increase the resistance in the highresistance direction of copper-cuprous oxide rectifiers.

A feature of this invention comprises manufacturing copper-cuprous oxidetype rectifiers from copper blanks formed from copper containing a smallamount ofanother metal, more par- .ticularly, cadmium.

A more complete understanding of the invention will be obtained from thedetailed description that follows, taken in conjunction with theappended drawing, wherein:

Fig. 1 is a cross-sectional view of a coppercuprous oxide rectifier inaccordance with this invention; and

Fig. 2 is a top plan view of the .device of Fig. 1.

Commercial copper having a high degree of copper purity with traces ofmetallic impurities totalingabout .04 percent, is in general use for themanufacture of copper-cuprous oxide rectifiers. In accordance with thisinvention, such copper, as received from the supplier, is remelted in areducing atmosphere, and then a small amount of cadmium is added to themelt. Sheet copper of about .05 inch thickness is formed from the alloy,andcopper blanks or washers punched therefrom. Such a copper blank orwasher I is then heat-treated, for example, by being placed in a firstfurnace having an oxidizing atmosphere at about 1000 C. for about eightminutes, then placed in a second furnace maintained at about 500 C. forabout five minutes, and then quenched in cold water. The copper oxidelayer 2 on the blank is then treated in any well-known manner to providea good contact surface thereon.

It has been found thatthe addition of cadmium in an amount up to about.5 per cent-by weight results in a rectifier having an improvedcharacteristic over rectifiers made from ordi- 5 nary commercial copperin that the resistance in the reverse current direction is increased.Rectifiers made from melts to which about .1 per cent, .25 per cent and.5 per cent cadmium were added gave this result. 10

It will be understood that this invention has been disclosed withreference to a preferred form thereof, and is to be considered aslimited inscope by the appended claims only.

What is claimed is:

1. A conductive device comprising a copper body containing cadmiumhaving an integral layer of the oxide of said body thereon.

2. A copper-cuprous oxide rectifier formed from a copper body containingcadmium.

3. A copper-cuprous oxide rectifier formed from a copper body containingup to about .5 per cent cadmium.

4. A copper-cuprous oxide rectifier formed from a copper body containingup to about .1 25

per cent cadmium.

5. A -copper-cuprous oxide rectifier formed from a copper bodycontaining approximately .1

. per cent cadmium.

. form the oxide layer thereon.

. GEORGE 0. SMITH

